Remove translations in progit.asc once asciidoctor >=2.1.0 is released

[petk]

Describe the bug:

Once the newer version of Asciidoctor 2.0.18 (2.1.x) is released and used in this repository's Gemfile, translations in the progit.asc file can be removed. I'm just noting this here for future reminder.

https://github.com/asciidoctor/asciidoctor/releases